In cotton picking machines of known design, such as exemplified by the Model 2055 Cotton Picker available from Case Corporation, cotton fibers are harvested from mature cotton plants by rotating spindles that contact the cotton bolls and strip the fibers from the plants. These spindles extend horizontally and rotate about a generally horizontal axis on vertical columns, with typically 18 spindles being arranged vertically on each column. These columns are themselves rotated about vertical axes arranged in parallel around the periphery of vertical picker drums, with five or more such drums being provided on the front of a typical picking machine. In addition to rotating about their respective axes, the columns of spindles in each drum revolve about the vertical axis of the drum as the picker advances through a field of plants, causing each rotating spindle to sweep through a revolutionary path in a horizontal plane.
The revolutionary path of the spindles is designed to produce a low relative velocity between the spindles and the cotton plants to allow the spindles to strip the cotton fibers from the plants by their horizontal rotation. At another location on their revolutionary path each column of spindles passes a column of doffers where the cotton fibers are doffed from the spindles and blown into a hopper by an air stream from a fan. Because the spindles tend to accumulate plant juices, dust and debris from the cotton plants, pads are provided at still another location in the revolutionary path of the spindles to contact and apply moisture to the spindles, thereby reducing the accretion of foreign materials that would otherwise reduce the harvesting efficacy of the spindles. These pads are generally arranged horizontally in a vertical column such that one pad contacts each spindle as the spindle sweeps past in its revolution within the drum. A detailed description of a cotton picking machine of the type described is provided in U.S. Pat. No. 4,905,464 issued to Thedford on Mar. 6, 1990, and of common ownership with the present invention. The entire disclosure of U.S. Pat. No. 4,905,464 is hereby incorporated into the present disclosure by reference.
In such cotton picking machines a spindle moistening system is provided that includes a tank for moistening fluid, a fluid pump coupled to the tank, a fluid conduit for directing fluid from the pump and a flow control valve connected to the conduit for manually setting the fluid flow rate. Downstream of the flow ,control valve the fluid is directed to a distribution manifold and, from there, to conduits feeding each pad. Such systems may also include a conventional pressure gauge for reading the fluid pressure in the vicinity of the flow control valve.
While generally effective for supplying moisture to the rotating spindles, such moistening systems have limitations and drawbacks. The use of an in-line flow control valve to regulate the pressure and flow of fluid to the moistening pads affords only a very rough, open loop control of moistening. Changes in the pressure of the moistening fluid, and hence in the flow of fluid to the moistening pads, may occur during operation of the machine and must be corrected manually by readjusting the flow control valve. Reasons for such pressure changes typically include a decreasing level of fluid in the reservoir, fluctuations in the supply voltage to the pump, and temperature changes during operation of the picker. Moreover, while in certain circumstances it would be desirable to flush the moistening system by momentarily increasing the fluid flow to the moistening pads, known moistening systems do not provide a convenient means for performing such flushes.
The present invention is directed to overcoming the drawbacks of the existing techniques set forth above. In particular, the invention is directed to a cotton picker spindle moistening system employing a control system to provide feedback control of the pressure and flow rate of the moistening fluid.